1. Field of the Invention
The present invention relates to HF-band wireless communication devices and particularly to HF-band wireless communication devices preferably for use in an RFID (Radio Frequency Identification) system.
2. Description of the Related Art
In recent years, as an information management system for articles, the RFID system has been in practical use which establishes communication between a reader/writer for generating an induced magnetic field and an RFID tag (also referred to as “wireless communication device”) attached to an article in a non-contact fashion with the use of an electromagnetic field in order to transmit predetermined information. The RFID tag contains the predetermined information and includes a wireless IC for processing predetermined radio signals and an antenna for carrying out transmission and reception of high frequency signals.
WO 2011/108341 discloses a HF-band RFID tag (wireless communication device) which includes a wireless IC for processing radio signals, a feeder circuit board on which the wireless IC is mounted, and a coil-shaped antenna pattern. In this device, a loop-shaped electrode which is coupled to the wireless IC is provided in the feeder circuit board. With only the loop-shaped electrode, the communication distance is short. However, the loop-shaped electrode is coupled to the antenna pattern via a magnetic field, and due to this feature, a long communication distance is achieved by utilizing the antenna pattern as a resonant booster.
In the wireless communication device, magnetic field coupling of a resonance circuit of the feeder circuit board and a resonance circuit of the coil-shaped antenna pattern is utilized, and therefore, power loss is likely to occur. Meanwhile, as for stabilization of the resonant frequency in the device, it is necessary to arrange the loop-shaped electrode and the antenna pattern with high accuracy. This is because the degree of coupling can vary depending on the arrangement relationship between these elements.